1. Field
The following description relates to a reference current generating circuit with process variation compensation.
2. Description of Related Art
In general, an analog radio frequency (RF) circuit uses a reference voltage and a reference current to operate in a stable condition. Such a reference voltage and a reference current are affected by a source voltage, temperature, and process variations.
In particular, a complementary metal-oxide semiconductor (CMOS) based current source circuit appropriately mirrors the reference current and includes a reference current source. When a bandgap reference (BGR) is used, the reference voltage and the reference current, which are very stable with regard to temperature, and the source voltage, may be generated.
Typically, a circuit generating the reference current may be designed in consideration of process, voltage, and temperature (PVT) variations. Examples thereof include a current source having proportional to absolute temperature (PTAT) characteristics, a current source having characteristics independent of a change in temperature, and the like.
In general, a current source having the lowest amount of change is ideal for source voltage (V) and process variations (P) among the PVT items. For temperature (T), a PTAT current source or a current source independent of temperature characteristics may be used according to characteristics required by an analog or RF circuit supplied with the reference current.
The bandgap reference generating the reference current source may be used to meet the temperature characteristics, and a low drop out (LDO) regulator providing a more stable source voltage with respect to a change in the source voltage may be used. However, even in a case in which a current source having a small amount of change is used, when the current source includes a resistor that causes process variations, a problem occurs in that there is a limit in reducing dispersion due to the process variations. As a result, a yield may be decreased.